Optical spectroscopy is widely used in scientific research, as well as environmental, medical, security and military applications. Known spectrometers and spectral imagers are applicable to astronomy, medical diagnostics (e.g., measuring blood oxygenation), military remote sensing, forensics, paints and textiles, and pollution detection (e.g., lead and mercury levels in water), to name a few.
Mobile communication devices, such as mobile phones, are often equipped with a built-in digital camera that can be used for imaging. The present inventors realized that with the addition of an optical spectroscopic module, a mobile communication device could be utilized as a portable spectrometer as well as a multimodal imager that acquires spatial, spectral and polarization information with a removable module. Some effort has been made to integrate an optical spectroscopic module with a mobile communication device in order to develop a portable, stand-alone spectroscopic device. In such integrated systems, a received optical signal is separated into a plurality of wavelength components, which are then measured. Therefore, to obtain a spectral image in such known systems, optical images, corresponding to each of the plurality of wavelength components, must be combined. Moreover, these systems are designed as a single, integrated device. In some known systems, the mobile communication device is physically modified to include an integrated wavelength selective element, as well as a built-in digital camera, in order to obtain a spectrum of an optical signal. Such integrated designs, however, lack in convenience. Moreover, it is difficult to implement or retrofit mobile communication devices already existing in the market, which may result in reduced functionality of the original mobile device. Furthermore, such known mobile device based systems can only obtain spectral information in a single-frame, or, a combination of spectral and spatial information in a series of multiple frames. The acquisition of only spectral information, via a mobile communication device of known systems, while perhaps beneficial for some practical applications of optical spectroscopy, is limited because spatial information is not also acquired at the same time. Thus, such known systems leave room for improvement. Without the acquisition of both spectral and spatial information, variations in spectral signatures as a function of position and time may be obscured because both pieces of information cannot be obtained in a single frame of acquisition. Furthermore, such known systems do not have the capability to acquire polarization information in the same frame, which is another commonly used source of information to characterize objects and distinguish between them. It is clear to those familiar with the state of the art that the invention and claims presented herein are readily applicable to “stand-alone” modules that may consist of a sensor external to the digital camera already contained in mobile computing devices that can be connected, for example, via wired (such as USB port) or wireless connections such as blue tooth to the mobile device to harness the computing capability. Although the present invention and claims also apply to such aforementioned embodiments, these are likely to drive up cost and complexity for consumers and other non-specialist users that are envisioned as the potential beneficiaries of the current invention that describes a modular platform compatible with sensors and imaging assemblies already contained within commercially available mobile computing devices.
Thus, a need exists for a portable spectroscopic device that acquires spatial and spectral information in a single frame of image capture. A further need exists for a portable spectroscopic device that obtains polarization information along with spatial and spectral information in the same frame of data acquisition. Yet a further need exists for a portable spectroscopic device featuring a removable dispersion element.